Motor operated circuit breaker mechanism



Oct. 7, 1941. w. A. ATWOOD ETAL 2,258,233

MOTOR OPERATED CIRCUIT BREAKER MECHANI'SM- Original Filed Feb. 23, 1939I lnventqrsz Winfield A.Atwood, Joseph W.Sea'rnan,

y W MMZM Their Attorney.

Patented Oct. 7, 1941 UNITED STATES PATENT OFFICE MOTOR OPERATED CIRCUITBREAKER MECHANISM Original application February 23, 1939, Serial No.257,914. Divided and this application April 24, 1941, Serial No. 390,184

4 Claims.

Our invention relates to motor operated circuit breaker mechanisms, andhas for its principal object the provision of an improved motor operatedcircuit breaker mechanism that is symmetrical and compact, positive andefficient in operation, and wherein the motor actuating unit can bemounted in detachable interchangeable relation to the circuit breakerproper for ready servicing and replacement.

This application is a division of our application Serial No. 257,914,filed February 23, 1939, for Circuit breaker operating mechanism.

In accordance with our invention, the motor mechanism, includingsuitable thrust transmitting structure, is mounted in a frame or supportthat is adapted to receive in interchangeable detachable relation thecomplete motor unit. The motor unit is detachably related to the thrusttransmitting structure so that it can be readily interchanged orreplaced as desired without disassembly of the thrust transmittingstructure.

Our invention will be more fully set forth in the following descriptionreferring to the accompanying drawing, and the features of novelty whichcharacterize our invention will be pointed out with particularity in theclaims annexed to and forming a part of this specification.

Referring to the drawing, Fig. 1 is a perspective extended view, partlyin section and partly diagrammatic of an electric circuit breakermechanism embodying the present invention, and Fig. 2 is a sideelevational view of the motor mechanism unit of Fig. 1.

The complete operating mechanism illustrated by way of example comprisesan interchangeable motor actuating unit generally indicated at l, a mainoperating toggle 2, and a tripping device for the toggle mechanismgenerally indicated at 3. The electric circuit breaker to be operated isshown at 4. Certain features of this mechanism are disclosed and claimedin Patent No. 2,152,453, issued March 28, 1939, to W. A. Atwood and G.Rudolph for Operating mechanism, and assigned to the same assignee asthe present invention.

The actuating unit I comprises a reciprocally guided plunger orcrosshead 5 that is connected through a slotted link 5' and cam I to themotor operating unit E5. The motor unit may be of the type disclosed andclaimed in Linde Patent No. 2,034,145, granted March 17, 1936, forOperating mechanism wherein an automatic brake generally indicated at 6'is interposed with respect to the cam shaft 1' and the motor proper.Suitable reduction gearing for the cam shaft is also generally indicatedat 6". The link 5' carries a cam follower or roller 8 for coacting withthe cam l, and the link is slotted at 5" for re ceiving the cam shaft 1.This not only provides guiding means for the link 5' but makes thedesign more compact. The link 5 and the crosshead 5 are detachablyinterconnected as by a removable pin 2' so that the cam shaft and motorassembly can be removed Without disassembly of the linkage 2.

Referring more particularly to the thrust transmitting structure, themain operating toggle at 2 comprises a pair of interconnected links Hand I2 that are operatively connected to the crosshead 5 by a link 9 atthe toggle joint or knee H3. The link 9 is detachably connected to thecrosshead 5 by a pin 9 that extends beyond the crosshead for a purposehereinafter described. The link I l is connected to a guide link I3having a fixed pivot at M, and the link I2 to a crank l5 that isrotatable on a shaft It.

The crank l5, which is operated by the toggle 2 in response to operationof the actuating unit, i. e., by rotation of the earn 1, comprises agenerally U-shaped member having substantially parallel sides l5 throughwhich the shaft l6 extends, interconnected by an integral transversestrip I5" extending parallel to the shaft. The crank at one side isprovided with a cam surface I! adapted to coact with a circuit breakercrank 18 which is rigidly connected through a rotatable countershaft E9to the movable arm 25 of the circuit breaker A. When the crank I5 isrotated clockwise as viewed by straightening of the main toggle Hl2 inresponse to elevation of the crosshead 5 by the cam l, the cam face I!bearing on the roller iii of the breaker crank rotates the breaker shaftIS in counterclockwise direction whereby the movable contact structure2B of the circuit breaker 4 is moved into contact engagement with thestationary contact structure 2!. This movement, or working stroke of thebreaker structure 20 is generally in opposition to spring pressuretending to bias the breaker to open circuit position.

For the purpose of holding the toggle i [-12 at the pivot 13 inthrust-transmitting position with respect to the crank l5 the toggleguide link I3 is related to suitable latching and tripping meanscomprising a link 22 connected to the toggle pivot l3 and to a latch 23having a fixed pivot at 24. The members 2'2 and 23 are suitablyinterconnected as at 25 for insuring a force-reducing connection.C'oacting with the latch 23 is a rotatable tripping shaft 26 to which issecured a detent member 21 adapted to engage the latch 23 at its notchedportion 28.

In the position shown collapse of the toggle ll-l2, that is,counterclockwise rotation of the toggle pivot l3 and dropping of theknee joint, is restrained by the latch 23 and detent 21. Trippingmovement, that is, counterclockwise rotation of the tripping shaft 26,effects release of the latch 23 so that it is free to rotatecounterclockwise for releasing the pivot l3 and permitting openingmovement or collapse of the toggle.

In the closed circuit or restraining position shown the tripping means 3is latched and the toggle is held in an underset extended position by aprop 29 adapted to support the knee id of the toggle. The prop is shownas being secured to a rotatable shaft 39 that is resiliently connectedby a spring 3|, as illustrated, to the tripping shaft 26 so as tofacilitate resetting of both the prop and the latching means after acircuit opening or releasing operation of the mechanism.

Referring more particularly to the tripping means, the tripping shaft 26is provided with an offset portion or arm 32 for coacting with atripping means 33 that is shown as a solenoid energized from a controlsource through a switch The member 32 may also be engaged by manualtripping means indicated at 32'. A conventional overload tripping coil35 shown as energized from the main circuit at 4' may also coact withthe tripping shaft at 36. When the breaker is closed as shown in Fig. 1and the cam l is in the position shown, tripping can be accomplished byrotating the tripping shaft 26 counterclockwise by any of the meansdescribed.

The breaker crank I 8 is also connected to the crank I5 by means of acompression spring 3"! guided on a member 38 engaging one end of thecrank l5 and having a guided sliding connection at 39 with an arm of thecrank 18. circuit position shown the spring 31 is under compression sothat immediately upon release of the tripping latch, opening movement ofthe toggle ll-l2 is accelerated by the stored spring energy, resultingin rapid movement of the cam surface I! away from the roller 18. Thecircuit breaker crank I8 is also acted upon through out the breakeropening stroke by the spring 3.! tending to accelerate separation of thecontacts 20 and 2|. During the closing operation when the crank I5 isrotated clockwise the spring 31 is placed under compression by reason ofthe comparatively long lever arm of the crank l8 acting in the oppositedirection on the spring.

When the toggle l|l2 is released in response to a tripping operation,the toggle pivot l 3' is free to rotate counterclockwise about pivot 14thereby causing shifting of the toggle knee Hi from the end of the prop29 and permitting dropping of the knee and opening movement of thetoggle. The prop 29 is suitably shaped, as illustrated, for permittingfree movement of the toggle knee l0 alongside the prop. Emergency manualclosing is of course possible by lifting the crossheads by suitablemeans.

The resilient connection 3! between the trip shaft 26 and the prop shaft30 biases the tripping detent into latching engagement after the latch23 in dropping pushes down on and passes by the latch detent 2'1, thelatter snapping into reset position due to the bias of spring 3!. At thesame time the spring 3! exerts a counterclockwise bias on the prop 29urging it against the side of link 9 so that when the links II and 12are raised to toggle position in a subsequent clos- In the closed ingoperation, the prop 29 is snapped beneath the toggle knee ID to hold themechanism in closed position independently of the actuating means. Astop member 29' is provided for preventing movement of the prop beyondthe toggle knee.

It will therefore be noted that the mechanism is trip-free in operationsince at any time during the closing stroke, release of the toggle pivotl3 in response to a tripping operation causes freeing of the toggle andopening of the circuit breaker. The opening speed is very rapid due tothe fact that the main toggle can simply shift laterally off the prop 29to open the breaker, since complete collapse of the toggle is notrequired until the linkage is to be reset. Actual breaking of the toggleis therefore unnecessary to initiate the opening movement. In the caseof trip-free operation as the crosshead 5 is elevated by the motoroperated cam I, the toggle remains in the extended position shown duringthe opening stroke. The resetting operation then takes place as thecrosshead is lowered when the roller 8 drops to the low point of the camI and the latch 23 drops to its latching position. This resettingoperation is also followed for normal tripping. The circuit breaker can,if desired, have separate means such as springs for normally biasing thesame toward open circuit position.

The mechanism proper above described, apart from the motor actuatingunit, is permanently mounted in a frame 44 as shown by Fig. 2 comprisinga pair of spaced side plates suitably secured as indicated to a supportor panel 45. The various shafts and pivots of the mechanism can bejournalled in the side plates so that the mechanism proper is a compactand integral unit.

Referring now to the motor actuating unit, it includes a compact castingor housing 46 for the reduction gearing and also for supporting themotor base at 41. Fig. 2 illustrates more specifically the applicationof the motor operating device and unit to the above described mechanism.As illustrated, the electric motor actuating unit comprises a unitarystructure that is secured at 48 to the mechanism frame 44. The securingbolts or the like at 48 can conveniently be the same bolts for securingtogether the parts of the housing 43. The pins 2 and 5, which extendthrough and beyond the crosshead at opposite sides thereof are guided inslots 4'! which are formed in both side plates of the frame 44. Theslots are open at the top so that the crosshead can readily be insertedin the frame.

As illustrated by Figs. 1 and 2, the actuating unit includes an electricmotor 50, the rotor shaft 5i of which is vertically positioned andprovided with a worm drive 52 for coacting with a worm gear 53 that issecured to the cam shaft 1'. The cam I mounted on the shaft '1' is ofsuitable design for applying the breaker closing force and is actuatedin clockwise direction as indicated upon energization of the motor 50.The cam and its associated shaft and operating gears included in thecasing 46, together with the motor and self-contained brake unitindicated at 6, are mounted as a complete and detachable unit on theframe 44.

In a motor operated cam mechanism of the character above described, themotor is energized for predetermined rotation of the cam, after whichthe motor is deenergized and the rotating parts brought to a quick stopby the automatic brake indicated at 6 as described in the aforesaidLinde patent. The cam follower or roller 8 rides from the low point ofthe cam I to the high point, thereby raising the crosshead and closingthe breaker at 4. As illustrated, the slotted link 5 is guided forreciprocal rectilinear movement both by the cam shaft and by the guidedcrosshead 5 so that the cam follower is limited to reciprocalrectilinear movement.

When the breaker is closed, the cam 1 is rotated somewhat beyond itshigh point before being checked by the brake as shown by both Figs. 1and 2. The breaker in this position is held closed by the prop 29.Therefore, when the breaker is tripped, the crosshead 5 is free to dropand the linkage is thereupon automatically reset in the mannerpreviously described. When the motor actuating unit is to be removed forservicing, inspection or replacement, the bolts 48 are simply unloosenedand withdrawn from the frame at the three points indicated. The pin 2'is then withdrawn freeing the link 5' so that the complete actuatingunit including the cam can be lifted from the frame without disturbingthe thrust-transmitting mechanism or the circuit breaker.

It should be particularly noted that the motor mechanism above describedis rugged and compact and symmetrical with respect to the actuatingforce. By avoiding unnecessary and complicated operating linkage andassociated structure, the actuating force is effectively and efiicientlyapplied, thereby securing a more compact and efiicient design for agiven power rating.

It should be understood that our invention is not limited to specificdetails of construction and arrangement thereof herein illustrated, andthat changes and modifications may occur to ne skilled in the artwithout departing from the spirit of our invention.

What we claim as new and desire to secure by Letters Patent of theUnited States is:

1. Circuit breaker operating mechanism comprising a supporting frame,thrust transmitting means mounted in said frame, a member guided forreciprocal rectilinear movement in said frame for actuating said thrusttransmitting means, and an electric motor actuating unit adapted to bemounted in said frame in detachable interchangeable relation thereto,said unit including a cam disposed in operativ relation to saidretilinear guided member.

2. Circuit breaker operating mechanism comprising a supporting framehaving spaced side members, thrust transmitting means mounted in saidframe between said members, a member guided for rectilinear movementbetween said side members for actuating said thrust transmitting meansso as to close the circuit breaker, and an electric motor actuating unitincluding a cam adapted to be mounted in said frame between said sidemembers in detachable interchangeable relation thereto, said cam beingoperatively related to said guided member so that rotation of said camto the high point thereof is effective to close said breaker androtation of said cam to the low point thereof permits resetting of saidthrust transmitting means, and means for readily detaching said motoractuating unit with respect to said frame whereby said unit can belifted from the frame independently of said thrust transmitting means.

3. Circuit breaker operating mechanism comprising a supporting frame,thrust transmitting means mounted in said frame, a crosshead memberguided for reciprocal movement in said frame for actuating said thrusttransmitting means, an electric motor actuating unit including a cam andcam shaft operatively connected to the motor adapted to be mounted insaid frame in detachable interchangeable relation thereto, a camfollower, and a link interconnecting said crosshead member and camfollower, said cam shaft extending through an aperture in said link andguiding said link so that said cam follower is operated substantially ina rectilinear path for actuating said crosshead member.

4. Circuit breaker operating mechanism comprising a supporting frame,thrust transmitting means connected to the circuit breaker mounted insaid frame, an electric motor actuating unit including a motor,reduction gearing, a cam and cam shaft adapted to be mounted in saidframe in detachable interchangeable relation thereto, said unitincluding securing means for detachably connecting said unit to saidframe so that said unit can be lifted from said frame withoutdisassembling said thrust transmitting means, and means operativelyrelating said cam to said thrust transmitting means for closing thecircuit breaker.

WINEFIELD ,A. ATWOOD. JOSEPH W. SEAMAN.

